Function Sequence And Possible Faults - Viessmann Vitodens 333 Service Instructions Manual

Initial start-up, inspection, maintenance
Further details regarding the individual steps

Function sequence and possible faults

For further details regarding faults, see page 74.
Control unit is-
sues heat de-
mand
Yes
Fan starts
Yes
Differential pres-
sure sensor en-
ables start (0.75
V across term-
inals X8.5 and
X8.6)
Yes
Ignition
12
Gas restrictor allocation
Gas type
&
Natural
gas E
&
Natural
gas LL
& LPG P
Display screen
No
after approx. 51 s
No
Fault
F5/F9
after approx. 51 s
No
Fault
E6/F5
Fault
No
F4
(cont.)
Internal 7
gas restric-
tor
mm 4.8
mm 5.3
mm 3.7
Remedy
Increase set
value and ensure
heat is drawn off
Check fan cables
and plugs
Check fan cables
and fan plug-in
connections,
check fan
Check ignition
module (control
voltage 230 V)
across terminals
X2.1 and X2.2